Electrical etching machine



March 8, 1.938. G. F. JoHNsToNE 2,110,487 ELECTRICAL ETCHING MACHINE Filed' March 25, 1935 3 Sheets-Sheet 1 'I f f Mw 13u/enjoy n 6607596127 fkmf/Zne it/wss March 8, 1938. G, JOHNSTONE 2,110,487

ELECTRICAL ETCHING MACHINE Filed March 25, 1935 3 Sheets-Sheet 2 March 8, 1938. G. F. JoHNsToNE ELECTRICAL ETCHING MACHINE 3 Sheets-Sheet 5 Filed March 25, 1935 III I.

f o giga/67a r x 60 QI/a.

Patented Mar., 8, 1938 UNITED STATES Msi OFFICE Application March 25,

13 Claims.

The invention relates to electrical etching machines which usually employ an anode, a cathode and an electrolyte and has as its principal object the provision of a method and means capable of accomplishing the production of a plate for use in the printing industry and which materially reduces the time period necessary for this accomplishment.

The invention is particularly adapted for use lo in the production of zinc printing plates which heretofore could not, to my knowledge, be successiully produced by electrolytic action.

It is another object of the invention to accomplish etching of a plate under pressure, above i5 atmospheric pressure, the pressure being applied to the electrolyte during the etching operation.

It is another feature of the invention to provide means for cooling the electrolyte to thereby maintain the electrolyte at a temperature sufficiently low to prevent dissolving or removal of insulating material applied to certain portions of the plate to insulate same against the etching action.

The invention has as another object the provision of means for cooling the electrolyte by subjecting the latter to the eiects of a cooling agent either during or subsequent to the etching operation.

The invention has these and other objects all cf which will be explained in detail and more readily understood when read in conjunction with the accompanying drawings which illustrate various embodiments whereby the various objects of the invention may be accomplished it being therefore manifest that other arrangements may be resorted to without departing from the spirit of the appended claims forming a part hereof.

Figure 1 is a rear elevation of an etching machine, partially in section illustrating a certain combination and arrangement of elements for'accomplishing the above enumerated and other objects. n

Figure 2 is a partial end View of the structure illustrated in Figure 1 showing certain portions in section.

Figure 3 is -a sectional view taken on line 3-3 of Figure 1.

Figure 4 is a perspective view showing a detail of the construction illustrated in Figure 3.

Figure 5 is a sectional view of a terminal employed in the device.

Figure 6 is a perspective View of a cathode 55 employed in the machine.

1935, Serial No. 12,923

Figure 7 is a side view similar to Figure 2, showing a modified arrangement of elements.

Figure 8 is a front view of another structure whereby the invention may be accomplished; and

Figure 9 is a sectional view of a fragment of. an etching machine showing a modified cooling structure which may be employed for cooling the electrolyte.

It may be here stated that one phase of the invention contemplates the provision of means for supplying air under pressure above atmosphericl pressure to a receptacle containing an electrolyte, anode and cathode, and to accomplish etching under this pressure and another phase of the invention is to maintain the electrolyte in a relatively cool condition preferably between 70 and 100 F. which temperature it has been found' does not effect removal of the insulating or protective coating applied to certain parts of the plate to be etched.

The invention also contemplates the accomplishment of a cooling effect, by means of any one of a plurality of' means which will hereinafter be referred to in detail. The apparatus disclosed in Figures 1 and 2 for accomplishing the above enumerated and other objects, contemplates withdrawal of a portion of the electrolyte from the receptacle after completion of an etch and subjecting the electrolyte to the cooling effect of a cooling medium and then returning the electrolyte to the receptacle for subsequent use.

The apparatus just referred to, also contemplates the provision of means for supplying air under pressure above -atmospheric pressure to the receptacle, containing the electrolyte so that the electrolyte is subjected to the influence of this pressure during the etching operation. The structure illustrated in Figures 1 and 2, contemplates the utilization of a receptacle Ill, which is lined with rubber or some other suitable insulator designated II which protects the metallic receptacle against electrolysis during the etching operation. This receptacle has a closure I2, the latter being hinged to the receptacle I0 as indicated at I3, it being understood that a suitable gasket I4 is interposed between the flanges I5 and I6, which flanges are respectively formed upon the receptacle and the closure.

The closure I2 is held relatively to the receptacle to prevent leakage of air from the receptacle through the medium of a plurality of Wing nuts II which releasably hold the cover in tightly closed relation with the gasket I4 which thus preventsleakage of air from within the interior of the receptacle. A motor generator I'8 isV employed. 'I'his m'otor generator has a bus-bar I9 connected therewith,'tc which conductors or barsl such as and 2| are connected to complete an electrical Y connection with the cathode 22 The cathode in the present instanceisbf a perforated character and is located below the level of the liquid electrolyte contained in the receptacle l0, the plate to be etched or anode is designated 23 and is supported in the receptacle Yat one side or above the cathode. the anode in` proper relation to the cathode and Within theV electrolyte.

'Ihis meansinvolves theuse of adjustable ele- Vments such'as thoseA respectively designated 24 and 25 which are'mounted foradjustment relatively tofeachother to thus provide a support Vcapable of adjustment to accommodate a plateV of a length and width of that designated 23 or one of another dimension. v. y

These adjustable elements 24 and 25 are slidably mounted in guide-ways 26, located at the front andrear and interiorly ofthe receptacle Il).

These Y guides 2liA are,1 in .the present instance, Y

formedV of bars or angle iron members 21 and v28 as clearly shownY in'Figure 4. Manifestly` the adjustable elements 24fand 25 may be moved toQany desirable position along "the grooves f formed by the elements 21 and 28 and therefore these aiustable elements may b'earranged rela tively to each other t'o accommodate plates of various sizes or dimensions.. Y f

' A'terminal or contact element generally'desig-- nated 29,Y is carried by the cover 'orclosure I2 and is in turn electrically connected Ywith a terminal 29 extending from the motor generator I8', and therefore operation of the generator will cause current to ow from "the generator toy the] anode and through' the electrolyte to the cathode. The construction of the contact elementY 29'involvesV a cup-shaped 'flexible memberl 30.which is preferably formed of rubber or rubber composition and is securely connected withthe closure I2 through the connecting portion 3I thereof.

In the particular, contact element or terminal 29 illustrated, ametallic sleeve 3211s' employedgin y which the contact element .33V is resiliently and reciprocably mounted. A coil spring 34 islprovided upon one lend ofthe contactelemerntv33 and this spring re-actsbetweenone end of the sleeve 32 andthe headorenlargement 35 provided upon the contact 33Y and allows'for reciprocable motion ofthe said contact. Y Y A The cup-shaped element surrounds the lower e end of the contact element: V33' and a part thereof also encloses the'sleever32, Vand since the part 3`I of the cup shaped element isinterposed between this sleeve andthe material of the coverk the' contact element 33 is thoroughly insulated from the remaining structure. In' the particular apparratus illustrated in Figures 1and-.2 for effecting etching of a plate, the m'otor generator designated I8 provides means for operating arsuction fluid pump A36 and also an air pump such as that designated 31. To this end the shaft of the motor generator is provided with pulleys respectively Y,

designated 33 and 39 from which belts respectively designated 40 and 4|areen'trained over pulleys respectively designated .42 and 43 to thus provide means for respectively drivingfthefluidpumpand air 'pump respectively designated 36 and 31.V f It is believedfevident that since the airpurnp'f31 isY connected with the interior. offthe receptacle I3, through the pipe VconnectionY 44, operation ofthe motor generator willintroducef air to the recepi Means isprovided for supporting o inthe printing industry.V

2,110,437 Y o Y tacle through this/connection and create a pressurein the receptacle above atmospheric pressure Vwhich is applied to the electrolyte contained inY the receptacle and therefore -wili'in this manner assist in reducing the Atime period necessary in whichV to produce a plateV having characteristics capable of use in the printing industry.

The air pump 31 is connected with the air inlet y Y through the pipe connections 45 and 46. A valve 41 is located between the outlet of the pump 3,1 and the in-let 44,v and therefore when the required pressure obtains within the receptacle III,

k the valve 41 is manipulated to close the same and prevent the formationof pressure in excess of a prescribed amount, indicated bythe pressure Y gauge v51 carried by the closure or cover I2.

It is evident that when the main line switch 48 andv the rstarting switch 49 are closed this will cause operation ofthe motor generator which causes current to be.` supplied to the anode,

cathode and the'electrolyte contained within the' receptacle I 0L It isfurther believedmanifest that the pump31 will atthis time also be actuated, and should thevalve 41 atl this time be open, air under pressure ispumped to the receptacle I0, which will thus supply Ythe required pressureto the receptacle Ii);V and the electrolyte Vcontained therein. vThis has been found notonly to increase production jof a plate, but in addition to make pos- Y sible the'successful production of a zinc printing plate' whichy heretofore could not, to my knowl- V edge, besuccessfully accomplished.

'plate occurs, this 'will expose those portions which it isdesired to protect against the etchingeffect and allow these portions to be etched away resulting in renderingthe plate worthless for use To eliminate this' disadvantage and maintain theelectrolyte ata certain relatively cool temperaturefvarious methods' mayY be resorted to,

that shown in the'structure illustrated inY Figures 1 and' A2 conte'mpla'tes'the utilization of areser- Voir 50;'inrwhich is contained` acooling coily 5I through which a cooling medium is circulated in engagement withaquantityof electrolyte con- Vtained'in thereservoir-50.' This reservoir 50 is connected with the interio'rofV the receptacle I0 Y Y by means of a pipe connection 52 having a valve` 53 interposed between the opposite ends of the pipe connection 52 and the reservoir 50( f An outlet Vpipe connection 54 extends 'fromfthe lower portion of the reservoir 50 tothe suction fluid pump generally designated 36. A fluid outlet pipe connection 55 extends from thepump 36' to the interior of the-receptaclelil, and a valve 56,

and fluid pump-*31. It is, of course, understood that Vduring the introduction of air 'tot the receptacle I0 the valve 56 is closed asis also the valve When the etching operation iscompleted the valve 53 is opened, the air pressure above atmospheric pressure contained `within the receptacle, causesa certainrquantity of the electrolyte to be forced from the receptacle intov'the reservoir 50 et Vis interposedl between the pump 36' and the air l If the plate is found in proper condition as to y depth, etc., it is removed from the receptacle and another replaced there-for, the receptacle is then closed, the valves 53 and 56 opened, operation of the pump 36 will draw the cooled electrolyte from the reservoir 50 and again introduce it in its cooled condition to that electrolyte remaining in the receptacle l0. After the reservoir has been emptied, the valves 53 and 56 are again closed and the valve 41 opened, so that the electrolyte now contained in the receptacle may have the required air pressure applied thereto to assist in accomplishing the etching effect.

The structure illustrated in Figure 7 contemplates the provision of means whereby a constant circulation of the electrolyte from the receptacle l is accomplished to effect cooling of the electrolyte. In this structure a cooling medium is circulated through the cooling coils 59 contained in the reservoir 60. To accomplish this constant circulation of the electrolyte as hereinbefore referred to, a pipe such as 6l is extended into the electrolyte. This pipe has a pipe connection 62 connected therewith which communicates with the reservoir B0, and is provided with the valve 63 which may be closed when occasion demands. An outlet pipe connection 64 extends from the reservoir 6U to the fluid pump 65, the latter of which has a pipe connection 66 extending into the receptacle I0. This last mentioned pipe connection E6 may be provided With a valve 61, so that circulation of the electrolyte may be arrested, which will thereby trap air above atmospheric in the receptacle should this at any time be found necessary or desirable.

The use of an air pump 68 as previously described is also contemplated in this structure, to provide means to supply air above atmospheric pressure to the interior of the receptacle. The apparatus illustrated in Figure 7 also involves the use of a motor generator designated 69, the latter being in electrical connection with the anode and cathode as hereinbefore explained.

It is understood that the device just referred to may have certain of the various elements and devices referred to in the explanation of the structure illustrated in Figures 1 and 2 combined therewith. The structure illustrated in Figure 8 contemplates a structure in which a cooling medium is circulated in effective relation with the electrolyte contained within a receptacle such as that previously referred to. The structure illustrated in Figure 8 for accomplishing this last mentioned advantage, may employ a tank within which a receptacle designated 'Il is mounted containing the electrolyte, anode and cathode.

This last mentioned receptacle has a closure 'l2 which may involve structural features such as explained in connection with the description of Fig. 1. The tank 'lll contains a suitable quantity of any desired cooling medium and for the purpose of simplicity of illustration a separate motor 13 is illustrated for actuating the uid pump 14, the later of which communicates with the interior of the tank 10 through the pipe connections respectively designated and 16.

Manifestly when the motor 13 is actuated the pump 14 will draw the cooling medium from the tank I0 through the pipe connection 'I5 and discharge same back into the receptacle 10 which will cause a constant circulation of the cooling medium as hereinbefore explained. It may be here stated that a cooling coil 'Il may be employed, the latter of which may be contained within a reservoir 18 as previously explained, however, any other desirable arrangement may be substituted for that shown.

In this structure as in others previously referred to it is contemplated to supply air under pressure above atmospheric pressure to the receptacle 1I, to this end a motor 19 may be employed for actuating the air pump 80. In this structure the pump 80 is connected through the medium of the pipe connections 8| to the interior of the receptacle 'I I. A motor generator 82 is employed, it being understood that proper electrical connections as previously explained are made from this motor generator to the anode and cathode, and it may here be stated that the pumps 14 and 8H may be actuated directly from the motor generator as explained in connection with previously referred to structures.

From the foregoing explanation of the structure illustrated in Figure 8, it is believed manifest that an arrangement is herein illustrated in which the cooling medium is constantly circulated in effective relation with the electrolyte, to thus maintain the latter in a relatively cool condition, which thus differs from that structure disclosed in Figure 'l in which the electrolyte is constantly circulated into effective relation with a cooling agent. Figure 9 the cooling 4element is located within a receptacle such as previously designated l0 and the cooling medium is circulated in effective engagement with the electrolyte, through a cooling coil 83 which Ais housed Within a receptacle such as I0.

The cooling fluid being circulated through the cooling coil 83 tothus maintain the temperature of the electrolyte relatively low. It is understood that a structure such as last referred to may have an air pump associated therewith yto subject the electrolyte to pressure above atmospheric pres-"- sure as previously explained.

From the foregoing description of the various In the apparatus illustrated in embodiments of the invention it is believed evident that, the various forms of the invention all lend themselves to the accomplishment of etching under pressure above atmospheric pressure and in addition disclose means for maintaining the electrolyte in a relatively cool condition so that constant etching may be accomplished Without resulting in an injurious temperature rise of the electrolyte which as before pointed out causes the insulating material applied to the plateto be etched to dissolve and become detached from the plate which thus exposes and allows etching of portions of the plate which should be protected against the etching action to accomplish the production of a printing plate.

Having thus described the invention what I claim and desire to cover by Letters Patent is:

1. In an etching machine the combination of a closed receptacle, an electrolyte in said receptacle, a cathode and a terminal for an anode extending into said receptacle and means for introducing air under pressure above atmospheric pressure to said-closed receptaclejto thereby apply pressure to said electrolyte. ..7 d 12. In an etching machine the combination; of a closed-receptacle,` an electrolyte inisaidreceptacle,

-a cathode anda terminal forananodeextending i intorsaid receptacle, means for introducing air under pressureabove ,atmospheric pressure toV said receptacle to'thereby vapply pressureto'said Y electrolyte and means associatedwithsaidgrecepf vtacle for cooling saidelectrolyte: c Y

3. VIn an etching Vmachinetheicombination of a' Y Yclosed receptacle sealed; against' the` escape'of air therefrom, an electrolyte and a termina1for-az cathodearranged insaid'receptacle and an air pump communicatingwith said receptacle Vand providing means for supplying air under` pressure i above atmospheric pressure to said closed recep. f

tacle.- v, ,Y

4. Anetching tion a receptacle Y,having a closure,v saidV closure preventing the scope of pressure therefrom', an

' ode arranged in said receptacle, means whereby l f1 5. An etching machine comprising in combina- Y electrolyte and terminals for yan anode and Vcathsaid electrolyte is circulated torand from saidY receptacleA and means'for applying air under pressure above atmospheric ypressure to saidelec trolyte. Y

tion Ya receptacle jsealedV against escape of/air therefrom; and terminals for an anodeand cath'- ode arranged ,in said receptacle, means for cirreceptacle, andra cooling agent surrounding-saidY receptacle,l means for circulating said cooling agent relatively tothe electrolyte, means for supplying air at a pressure above atmospheric pressure tofsaid closed receptacle andmeans for trapping said air in the receptacle.

7. An Vetching machinecomprising in combination a closed receptacle, a container in which said receptacle is located, an electrolyte and ter- Vrninals for anV anode and cathode arranged in said receptacle, and a colingagent'located in said vcontainer ineffectiverelation with said electrclyte,V means for circulating said coolingagentY relatively to the electrolyte, means for'supplying air at a pressure above atmospheric pressure toV machinercomprising in combina- Y carried by said closure.

receptacle.

said :closed receptacle. and means; for' trapping said air in the receptacle. l nl '8. In an etching machine, the combination of Y af'receptacle providing a container for an :electrolyte and air above .atmospheric pressure,A a yterminal -for an anode and a terminal for a cathode arranged in said receptacle and an` 1ndependently effective air pump for creating said vpressureY and a pump for :pumping liquid connected ywith said container.

9.` An `etching machine'comprised ofV a receptacle providing a; container for an electrolyte andV air,V at alpressure above atmosphericV pressure, terminals forv an anode and a Acathode in said receptacle, areservoir providing means for the reception` of-said electrolytel communicating with said receptacle, an air Vpump and a pump-for Y pumping V*liquid-,connected withv said container and meansffor Vindependently controlling] the effectofsaid'pumps.,A f 10. YAn etching machine comprised of a re:-

Yceptacle providing a container for an'electroly'te and air at a pressure above Vatmospheric pressure, terminals for anY anode andia cathode arranged in said receptacle, av reservoir communicating with. said receptacle providing meansvfor the receptionof said electrolyte, saidreceptacle having a ,closure forsealing said receptacle,Y one ofl said terminals' being carried by said closure., j 11; An etching machine comprised of a. receptacle providing an open container for an electrolyte, a terminal for a cathode arranged in said receptacle adjacent said opening, ai closure for sealing said opening and a. terminal for an anode v 12. An: etching machine comprising in combinationa receptacle providing a container for an electrolyte and air at a pressure above atmospheric pressure, a cathode arranged in saidre'- ceptacle, ananodersupportarranged at one side Yof'said cathode,: a closure for said receptacle and Ya Vterminal carried by said closure for cooperation' with said anode. Y

Y 13. etching machine. comprising in combination a recer'itacleV providing a container rfor an *electrolyte and air abovev atmospheric pressure, a closure ifor sealingx said receptacle, terminals for AanV anode and a cathodeiarranged in 'said receptacle; means for introducing saidairV at said f pressure to said'receptacle and meansfor releasing said pressure prior tothe opening of said rGoRGEiRJoHNsToNn. Y 

